Contact piece for the solderless connection of an insulated electrical conductor and method of using same

ABSTRACT

A contact piece for the solderless connection of an insulated conductor comprising a contact piece body having at least two cooperating cutting or knife edges serving to fixedly clamp therebetween the insulated conductor while penetrating through the conductor insulation.

United States Patent [1 1 Landolt CONTACT PIECE FOR THE SOLDERLESS CONNECTION OF AN INSULATED ELECTRICAL CONDUCTOR AND METHOD OF USING SAME [75] Inventor: Josef Landolt, Nafels, Switzerland [73] Assignee: F. Knobe] Elektro-Apparatebau AG,

Ennenda, Switzerland [22] Filed: Mar. 9, 1972 [21] Appl. No.: 233,144

[52] US. Cl. 339/97 P [51] Int. Cl. H01r 9/08 [58] Field of Search 339/95, 97-99 [56] References Cited UNITED STATES PATENTS 3,683,319 8/1972 Vigeant 339/97 R 1 Feb. 5, 1974 Pasternak 339/97 R Miller 339/97 R Dumeige 339/95 R Craddock et a1. .r 339/95 R Pohl 339/97 P FOREIGN PATENTS OR APPLICATIONS Netherlands 339/97 R Primary Examiner-Joseph H. McGlynn Attorney, Agent, or Firm-Eric H. Waters et a1.

ABSTRACT A contact piece for the solderless connection of an insulated conductor comprising a contact piece body having at least two cooperating cutting or knife edges serving to fixedly clamp therebetween the insulated conductor while penetrating through the conductor insulation.

4 Claims, 4 Drawing Figures PATENTED FEB 5 I974 sum 1 M a CONTACT PIECE FOR THE SOLDERLESS CONNECTION OF AN INSULATED ELECTRICAL CONDUCTOR AND METHOD OF USING SAME BACKGROUND OF THE INVENTION The present invention relates to a new and improved construction of contact piece or element for the solderless connection of an insulated electrical conductor as well as to an improved method of using such contact piece in an electrical device possessing a coil or windings.

Most of the state-of-the-art connection terminals require removal of the insulation from the insulated conductor prior to attachment as its connection end. Thereafter it is possible to attach the bare conductor end with the connection terminal. In this regard the conductor end can either be soldered or clamped at a clamping mechanism arranged at the connection terminal, the use of the clamping mechanism requiring separate manual manipulations. When using a conventional clamping mechanism of the prior art the conductor end is pressed by a screw against a counterpiece and fixedly clamped between such counterpiece and the screw.

Although a reasonably secure connection is established between the conductor and the above-described connection terminals, still the required expenditure in work and material is disproportionately great.

Apart from the above-discussed proposals which have appeared in this particular technology there are also known to the art different constructions of connection terminals by means of which the connection end of the conductor to the connected need not first have the conductor insulation removed. According to one prior art manifestation the connection terminals possess a clamping mechanism which fixedly clamps the conductor and simultaneously penetrates through the conductor insulation in order to come into physical contact with the conductor itself. However, such connection terminals are extremely complicated in construction and therefore expensive to manufacture. Ad ditionally, the contact which is established between the conductor and the clamping mechanism oftentimes is unsatisfactory.

According to another construction known in the art the connection terminals are formed of brass and possess a groove into which is placed the insulated conductor end. By means of a spot welding machine having a special tungsten electrode the brass is melted or fused at the region of the conductor end. The liquidous brass surrounding the conductor end burns the'conductor insulation and there is produced a good electrical con nection. However, when encountering situations having limited available space the use of a spot welding machine is not possible since the tungsten electrode cannot be applied to the terminal. Further, both procurement and maintenance costs of such type spot welding equipment are extremely high.

SUMMARY OF THE INVENTION Hence, from what has been stated above it should be apparent that the technology in this particular art is still in need of means for connecting insulated electrical conductors in a manner which avoids the aforementioned drawbacks and limitations of the abovediscussed prior art proposals. Therefore it is a primary 2 object of the present invention to effectively and reli ably fulfill the existing need in the art.

Still a further significant object of the present invention relates to an improved contact piece, affording rapid connection of an insulated conductor without the 1 need of first removing its insulation and providing for good electrical contact.

Yet a further significant object of the present invention relates to new and improved means for establishing a solder-free connection of an insulated electrical conductor in an extremely reliable, efficient and economical manner, not requiring complicated manipulations and manual operations, and without the necessity of having to previously bare the conductor.

It is still a further significant object of the present invention to provide a novel method of connecting an insulated electrical conductor in a manner requiring as few as possible manipulative steps, the connection work itself serving to remove the insulation from the conductor at the relevent location or locations, and establishing a good electrical contact.

Now in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the inventive contact piece for the solderless connection of an insulated electrical conductor is manifested by the features that it comprises at least two cooperating'cutting or knife edges which serve to clamp therebetween the conductor while penetrating the conductor insulation.

The previously mentioned method aspects of this development reside in the features that the required number of contact pieces are arranged upon a support and the conductors which are to be connected are secured thereto at the direct region of the outlet location of the conductor, and thereafter the conductors fixedly clamped between the cutting edges of the contact piece.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes referance to the annexed drawings wherein FIG. 1 is a fragmentary perspective view of a preferred constructional form of contact piece designed according to the teachings of this invention;

FIG. 2 is a fragmentary view of a wire coil with applied connection element having a contact piece of the type taught in FIG. 1;

FIG. 3 is a front view of the coil flange of the wire coil according to FIG. 2; and

FIG. 4 is a side view of the connection eleme t depicted in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in FIG. 1 thereis illustrated a preferred exemplary construction of inventive contact element or contact piece 1 with which there is connected a lacqueredor enamelled insulated conductor 2. The contact piece 1 is formedby a thin plate or the cutouts or notches 3 at one lengthwise side and the cutouts or notches 4 at the other lengthwise side are arranged in offset relationship with regard to one another, so that in each instance one cutout at one such lengthwise extending side is located between two cutouts at the opposite lengthwise extending side of the plate or sheet metal strip. In the embodiment under consideration the depth of these cutouts or notches 3 and 4 approximately corresponds to one-half of the width of such plate or strip 1a. By means of these cutouts 3 and 4 the strip or plate 1a is subdivided at each lengthwise extending side into individual sections 13 and 14 extending axially of such strip or plate.

The portion of the strip or plate 1a which possesses the cutouts or notches 3 and 4 is twisted or rotated with respect to the remainder thereof. Consequently, the neighboring sections 13 and 14 which are separated from one another by the respective cutouts or notches 3 and 4 are twisted or turned into different planes. These sections are spread apart in the same direction as the direction of twisting. Consequently, the cutouts 3 and 4 open so that the edges 5 at the underside of one respective section 13 or 14 and the edges 6 at the upper side of the neighboring section and bounding the associated cutouts intersect and form a respective substantially V-shaped cutout opening 3a and 4a, as illustrated.

During connection of the insulated conductor 2 such is drawn into the V-shaped openings 30 and 4a without previously removing the conductor insulation. During this pulling-in or drawing-in operation the conductor 2 is moved past the edges 5 and 6 acting as cutting elements or knives and which are disposed both above and below the conductor 2. Thus the conductor insulation is locally removed or shredded away at these cutting edges 5 and 6.

By virtue of the elastic characteristics of the strip or plate 1a a resilient restoring force having an effective direction opposite to the direction of twisting or rotating of the plate, acts upon the twisted portion of the plate which possesses the cutouts, and this resilient restoring force strives to rotate the twisted portion back into its original position. Consequently, oppositely directed forces act upon the neighboring sections 13 and 14 separated by a cutout or notch which tend to decrease the size of the V-shaped cutout openings 3a and 4a. The conductor 2 which has been drawn into such openings 3 and 4 and is situated between the cooperating pairs of edges 5, 6 is thus fixedly clamped between these pairs of edges in the manner of a scissor.

The conductor 2 can be quickly wound in helical fashion about the above-described connection piece without previously removing the insulation. Only with extreme difficulty is it possible for the thus clamped conductor 2 to be released from the cutouts and the electrical contact which has been established between the conductor and the contact piece is more than satisfactory.

Now in FIG. 2 there is illustrated a portion of a wire coil 20. The coil flange 21 for this coil or the windings and serving as a support possesses grooves 22 for receiving connection elements 23, only one of which has been illustrated in the drawings. These connection elements 23 are constructed at the side of the coil in the form of contact pieces 1 of the type depicted in FIG. 1 and possess a substantially U-shaped flexed contact element 24 which protrudes from the coil flange or support 21. This contact element 24 can be inserted into a bore 26 of a schematically illustrated terminal or clamp 25. The number of connection elements 23 is dependent upon the required number of coil connections. In the embodiment under consideration by way of illustration there can be attached to the coil flange 21 a total of four such connection elements 23.

By way of further explanation it is here remarked that in FIG. 3 there is illustrated the coil flange 21 in front view. The coil flange 21 which possesses a substantially rectangular cross-sectional configuration is equipped both at the upper side or face as well as the lower side or face with the grooves 22 and 22a respectively which in each instance form groove pairs for the reception of a connection element 23.

Now in FIG. 4 there is illustrated in side view one such connection element 23. The contact element 1 with the cutouts or notches 3 and 4 is constructed in the manner disclosed above in conjunction with FIG. 1 and is secured at an attachment portion 27 having a slot 28. A cam or nose 29 provided at the open end of the slot 28 laterally extends into the latter. The attachment portion 27 of the connection element 23, at the end situated opposite the slot 28, transforms into the previously mentioned U-shaped flexed contact element or portion 24. The connection element 23 is displaced by means of its slot 28 over the coil flange 21 into a pair of grooves 22, 22a. When the connection element 23 has assumed its end or terminal position within the slot 28 this connection element 23 engages by means of its cam 29 with a suitable non-illustrated recess provided at the coil flange 21, so that the connection element itself is fixed against displacement in the direction of the grooves 22 and 22a.

During assembly of the coil or windings 20 and the connection element 23 initially the connection element 23 is mounted in the described manner upon the coil flange 21 already equipped with the grooves 22 and 22a. The contact piece 1 then arrives at the direct region of the outlet or departure location of the coil wires from the coil or winding 20. Owing to the arrangement of the grooves 22 and 22a the mutual position of the connection elements 23 is exactly defined. The next step is to wind, as described, the free insulated ends of the coil wires in a helical fashion about the contact piece 1 and to draw such into the cutout openings 3a and 4a. Now it is possible to displace the clamps or terminals 25 which are associated with each connection element 23 and which can be assembled together into a terminal strip or block over the contact elements 24 in the manner of a plug connection. The contact element element 24, during such time as it is inserted into the bore 26 of the terminal 25, is slightly compressed and in its inserted position insures that there is established a good contact with the terminal 25 owing to its restoring spring force characteristics.

As a general rule the coils 20 with the mounted connection element 23 are subjected to a conventional impregnation process, wherein the connection element 23 with the exception of the edges of the contact element 24 are covered with an impregnation agent. Cleaning of the contact element 24 prior to the mounting of the terminal or clamp 25 is not necessary since the edges of the contact element 24 which are free of the impregnation agent and which bear against the inside of the bore 26 of the terminal 25 establish the requisite contact.

It is not absolutely necessary for obtaining an exact positioning of the connection element that the coil flange 21 be provided at its top and lower faces with the grooves 22 and 22a. It is also possible, for instance, to dispense with the use of the grooves 22a which appear at the bottom face of such coil flange.

The attachment portion 27 for attachment of the connection element 23 with the coil flange 21 can be provided, for instance, with flaps instead of with the described slot. These flaps are then inserted through slots at the coil flange and flexed over so as to bear against the bottom face of the coil flange so that the connection element 23 is properly positionally secured to the coil flange 21.

Furthermore, it is conceivable to construct the contact element 24 such that its end possesses a substantially bifurcated or forked configuration instead of the depicted U-shaped configuration. This bifurcated end can then be introduced into a suitable clamping mechanism which can be actuated for instance by means of a screw.

The construction of the connection element 23 at the side of the coil in the form of the contact piece 1 of the type disclosed in conjunction with FIG. 1 enables connection of the free wire ends of the coil with the contact piece only after there has been established the proper positional attachment of the connection element 23 with the coil flange 21. Because of the position of the contact piece 1 near the coil 20 it is possible to maintain small the length of the wire end to be connected which is between the coil and the contact piece. Since the connection element need not be displaced relative to the coil after completion of the assembling operation the wire can be guided between the coil and the contact piece without an addition to its length rendering possible such displacement. For these reasons there results a considerable saving in space, leading to a compact structural unit.

Furthermore, since the coil wire ends need not be soldered to the connection element there is advantageously dispensed with the need to resort to expensive measures for protecting the neighboring coil wire ends from the thermal effects caused by soldering. This in turn enables reducing the spacing between the connection elements themselves and between the connection elements and the coil.

The positioning of the connection elements and the aligned position of their contact elements provides the prerequisites for constructing the connection of the coil with an outer contact terminal in the manner of a plug connection.

By virtue of the described connection between the coil and the connection element, it is possible to change the position of the coil installed at an electrical device even after it has been mounted.

The possibility of shifting the position of the coil is of significance for certain induction devices, such as for instance choke coils and transformers of devices connected in series connected with discharge lamps.

ln particular with regard to such induction devices wherein the jacket or shell portion surrounding the core is formed of two bowl halves which consist of lam inations or sheet stacks which extend in the lengthwise and peripheral direction of thejacket portion, adjustment of the required electrical parameters by changing the position of the installed induction coil with respect to the jacket portion affords considerable advantages.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,

What is claimed is:

1. A contact element for the solderless connection of an insulated conductor comprising a substantially elongated contact body having two essentially parallel rows of substantially V-shaped cutout openings, each cutout opening being bounded by two cutting edges for fixedly clamping therebetween an insulated conductor wound around said contact body and inserted into said cutout openings, said cutting edges penetrating through the conductor insulation, each cutout opening of one row arranged between two neighboring cutout openings of the other row.

2. The contact element as defined in claim 1, wherein said contact body comprises a metallic strip having lengthwise extending sides, a respective row of substantially V-shaped cutout openings being arranged at said lengthwise extending sides in a direction substantially transverse thereto, the cutout openings of each row being substantially parallel to one another, said cutout openings subdividing said metallic strip into sections, and wherein neighboring sections are spread apart along each intermediately disposed cutout opening for.

forming said cutout openings.

3. The contact element as defined in claim 1, wherein said metallic strip has a substantially constant width, said cutout openings being arranged substantially perpendicular to said lengthwise ext-ending sides of said metallic strip and having a depth corresponding to onehalf of the width of said metallic strip, said sections of the metallic strip being spread apart in the same direction for winding the conductor around said metallic strip and inserting into the cutout openings in a substantially helically-shaped formation.

4. An arrangement for connecting the insulated conductors of coils or windings of an electrical device, comprising a support member of said electrical device, a number of contact elements equalling the number of conductors to be connected fixedly mounted on said support member and arranged at a spacing from one another, each contact element comprising a plug connector element and an elongated contact body having two essentially parallel rows of substantially V-shapecl cutout openings, each cutout opening being bounded by two cutting edges for fixedly clamping therebetween an insulated conductor wound around said contact body and inserted into said cutout openings, said cutting edges penetrating through the conductor insulation, each cutout opening of one row being arranged between two neighboring cutout openings of the other row, the plug connector elements projecting from said support member in substantially the same direction.

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1. A contact element for the solderless connection of an insulated conductor comprising a substantially elongated contact body having two essentially parallel rows of substantially Vshaped cutout openings, each cutout opening being bounded by two cutting edges for fixedly clamping therebetween an insulated conductor wound around said contact body and inserted into said cutout openings, said cutting edges penetrating through the conductor insulation, each cutout opening of one row arranged between two neighboring cutout openings of the other row.
 2. The contact element as defined in claim 1, wherein said contact body comprises a metallic strip having lengthwise extending sides, a respective row of substantially V-shaped cutout openings being arranged at said lengthwise extending sides in a direction substantially transverse thereto, the cutout openings of each row being substantially parallel to one another, said cutout openings subdividing said metallic strip into sections, and wherein neighboring sections are spread apart along each intermediately disposed cutout opening for forming said cutout openings.
 3. The contact element as defined in claim 1, wherein said metallic strip has a substantially constant width, said cutout openings being arranged substantially perpendicular to said lengthwise extending sides of said metallic strip and having a depth corresponding to one-half of the width of said metallic strip, said sections of the metallic strip being spread apart in the same direction for winding the conductor around said metallic strip and inserting into the cutout openings in a substantially helically-shaped formation.
 4. An arrangement for connecting the insulated conductors of coils or windings of an electrical device, comprising a support member of said electrical device, a number of contact elements equalling the number of conductors to be connected fixedly mounted on said support member and arranged at a spacing from one another, each contact element comprising a plug connector element and an elongated contact body having two essentially parallel rows of substantially V-shaped cutout openings, each cutout opening being bounded by two cutting edges for fixedly clamping therebetween an insulated conductor wound around said contact body and inserted into said cutout openings, said cutting edges penetrating through the conductor insulation, each cutout opening of one row being arranged between two neighboring cutout openings of the other row, the plug connector elements projecting from said support member in substantially the same direction. 